Evaluation of effect of protective case on wave propagation at 300 GHz

Evaluation of the effect of the protective case of an antenna on wave propagation by measurement is difficult when the wave length is 1 mm such as for a frequency of 300 GHz. Thus, evaluation based on simulation is required and electric parameters such as the complex relative permittivity are needed for the simulation. In this study, we first constructed a system for measuring complex relative permittivity. Then, we measured the complex relative permittivity of various materials that can be used in a protective case. It was found that our system could measure complex relative permittivity with high repeatability of less than 2.5%. Finally, we evaluated the effect of protective cases on wave propagation by comparing values of the S₂₁ obtained by simulation and measurement. The difference was within 2.0 dB at 300 GHz; thus, we concluded that the evaluation by simulation was valid.